[1] Some physicists, such as Lawrence Krauss, Stephen Hawking or Alexander Vilenkin, call or called this state "a universe from nothingness", although the zero-energy universe model requires both a matter field with positive energy and a gravitational field with negative energy to exist.
[3][4][5] Other cancellation examples include the expected symmetric prevalence of right- and left-handed angular momenta of objects ("spin" in the common sense), the observed flatness of the universe, the equal prevalence of positive and negative charges, opposing particle spin in quantum mechanics, as well as the crests and troughs of electromagnetic waves, among other possible examples in nature.
[4] In the subsequent decades, development of the concept was constantly plagued by the dependence of the calculated masses on the selection of the coordinate systems.
In particular, a problem arises due to energy associated with coordinate systems co-rotating with the entire universe.
[7] A first constraint was derived in 1987 when Alan Guth published a proof of gravitational energy being negative.
[7] In his book Brief Answers to the Big Questions, Hawking explains: The laws of physics demand the existence of something called 'negative energy'.To help you get your head around this weird but crucial concept, let me draw on a simple analogy.
This may sound odd, but according to the laws of nature concerning gravity and motion—laws that are among the oldest in science—space itself is a vast store of negative energy.